Thermally actuated voltage indicator



Oct. 6, 1953 C. W. KLUG 2,654,865

THERMALLY ACTUATED VOLTAGE INDICATOR Filed March 16, 1950 AAAAAA- r l ll l l l l WWB Patented ct. 6, 1953 UNITED sTAiS 'rnittMALnf A cTUATEnvon-TAGE INDICATOR Charles VIV. klug, Chicago, Ill'. aoneti-Moi it,195o, serial No. 150,013 3' claims: (o1. 324-1665 The present inventionrelates to e' thermally actuated voltage indicator more particularlysuited to giving indication of the'v battery charge' of a storagebattery in an automotive vehicle while the generator is supplyingcurrent to the 5 battery.

One of the greatest'failures'v of the'auton'iotive Vehicle is caused bya discharged battery and1 hence it is desirable tomaintaina fullycharged battery at au times. 1tl ofcourse is' known that 10 a yfullycharged battery has a higher V'oltageibetween its terminals Whilebeiiigi charged`-` evenA though the charging r'ateis' lower th'ana"partially charged battery but Subject t higher" charging rates.

As the battery is actn'inulatingvv a'k charge-the battery voltage willincreaseat afratheruiform rateouring the'ohargmg:pe'riod'with-e-sorewnet increased voltagerising"as`ithebatteryfappiioaches full charge.

It is therefore an objectofthepreisfritinvene tion to provide arelatively'si'irple device for dicating the charge'- oi.' a storageb'atteryjwhile" the battery is receivingl-chargingl curre'rntfrc'ma'Egenerator.

A further object`l of thepi'esentinventinfis'tb provide a them-'iallyAactuatedvoltage'indicator and application to'- showr the'relativefchargefo'f* a storage battery.

A further object of the presnt'inyeirtion' :isto 30 provide a thermallyactuatedf-vltagfrfieterhaving full scaledeilection"thro'u'`gh'arelativelyl small' portion of the full 4range =ofwcitag'ej values.'

Still another object? of thef'presentinvention is to provide means-forgi-vingfa4 re1ativei-i1idicat of the lbattery conditicnoffclrargebyaperiodi vl" hashing signal lampwherein theV v1las l`ies"" inc r' 2 ts`4in periodicity as the battery" voltage decreases? Other andfurtherobj'ectsi of the -present inve tion subsequentlywillbecome"apparntbyfrefer` ring to the description taken in conjunctionlwith the accompanying' drawings wherein:

Fig. 1 is a circuit diagram illustrating the principles of the presentinvention as appliedmtoa flashing signal voltage' indicator 'ofthe'thermally actuated type; and# Fig. e 2 is a circuit diagram andschematicV representation of a thermally actuated:"viilt'ageI meter.

Referring to Fig. 1 of the drawing, there has been represented anambient temperature compensated bimetallic element I I, which in itsmost usual form has a U-shape. One leg lof the U-shaped bimetallicelement II is aixed to a stationary surface at I2, and the other leg of55 2` the bm'eta'lli'c element" carries a movable contact I3.

The movable Contact' I3 is adaptedv to engage a' xed Contact I4' whichis connected in circuit with a signal lamp I5, having one terminalVgrounded and connected to the ground terminal of a storage battery I6.The y other terminal of the storage battery I6 is'connectd to aheatingwinding I 'I which has its other t'erminal' con nected to the contactI3', througg'fh one leg of the binletallic element" II. The' Contact I3and the leg'- of the bimjetallic element II are connected together toone terminal of a second heating yelement I Shaving its 'remainingterminalconnecte'd tothe ground terminalot the battery.

The resistance'for' heating effects of the heating elements I `I and I8Yarev selected as 'to provide a desiredmodeof op erettijr'rv Inparticular the heating element I8ihas a resistance value ap;

preciably greater than the resistance value of the signal lampj I 5Aseonnng a fully-'charged storage battery" le.

the' voltage supplied to v the heating elements I 1 ane.'Ifwhithtareiintaies across thebattery It wil'lbe vsufiju'zient to'maintain the contacts I3 and I4 separatedor at least separated for long'time battery voltage I6 is;` lessthan that obtained normally when thebattery is receiving charging current;l because" the5 battery i s ynotfully charged the" energy Supplied .to'tlie heating.' .elements I1 andlswiii be lms innoietfrt;to vmaintain the' oontacts I3'and I4 separated'fora'ny longtime intervals, Thus periodicallythecontacts"I3 .an'dll willoloseso that'ourreritnows to the lando I s thereby providing'inoreaseejourreht flow through the' heater' llw'hihbelds. ne the heatingsafer.- cientlyto 'again bring about separation of the or insubstantially discharged condition.

It therefore should be apparent to those skilled in the art that thethermally actuated voltage indicator represented in Fig. 1 provides arelatively simple visual indication for use on automotive vehicles whichis simple and economical to manufacture and which can be comprehended bythe user without referring to any particular indicia fon an instrumentscale.

Wherever it may nevertheless be held to be desirable to provide anindication by means of a pointer and dial, the arrangement shown in Fig.1 may be modied as illustrated in Fig. 2. For the purpose of indicatingsimilar components, similar reference marks have been applied toelements similar to that shown in Fig. l.

In lieu of the circuit for the lamp I5, there is provided a resistanceheating element I9 which y is wound about one leg of an ambienttemperature compensated bimetallic element 2I. As is common in the art,the ambient temperature compensated bimetallic element 2| may have aU-shape so that one leg is secured to aiixed point 22. Y

Another heater winding 23 has been shown .as being wound about the otherleg of the bimetallic element 2 I. The heating element 23 is connectedbetween the ground terminal of the battery IS and one terminal of theheater winding i8 of the bimetallic element Il. One leg of thebimetallic element 2I engages a lever 2d which actuates a pointer 25cooperating with an instrument scale 26.

The instrument scale 26 covers a relatively small portion of the fullvoltage range of the storage battery I6. Thus in one embodiment thescale 26 covers the range from 5.8 to 7.2 volts.

In operation, the system shown in Fig. 2 for a fully charged battery I6,produces infrequent closing of the contacts I4 and I3, so that thepointer 25 is positioned near the high end of the scale 26. If thebattery voltage I is below that of a fully charged battery the contactsI3 and I4 close at lesser time intervals so as to supply more heatthrough the winding I9 thereby to move the pointer 25 toward the otherend of the scale 26.

The desired degree of sensitivity is obtained by proper proportioning ofthe resistance heating Values on the heaters I'I and I8. The heatingelements I9 and 23 likewise are properly proportioned in order to obtainthe desired mode of operation, and generally are so arranged that whenboth heaters are in circuit, the .heater 23 produces a smaller heatingeffect than the heater In the present automotive vehicle an ammeter isfrequently provided to indicate whether or not charging current is beingsupplied to a battery. Where however, a battery is in a well chargedcondition, the current supplied is relatively low. The other times whenthe charge of the battery is low, the current supplied is now high butthis is confusing to the average automobile owner since he falls toappreciate the purpose and function of the circuit and volt relays ofthe voltage indicator.

It therefore would be less confusing and of much greater value toprovide an instrument of the type employing an arrangement such asrepresented by the pointer 25, and the scale 2B of Fig. 2. Thisarrangement has the advantage of spreading the indication of arelatively small voltage charge over a scale which by conventionalinstruments would be entirely impractical.

' temperature compensated bimetallic element Y having a heating elementarranged to be continuously energized from a voltage source, a secondheating element for said bimetallic element arranged to be normallyconnected in series with said rst heating element, and a shunt circuitincluding a pair of contacts controlled by said bimetallic element, saidsecond heating element beingarranged to be shunted thereby at aperiodicity proportional to a decrease in Voltage oi the voltage source.

2. The combination comprising an ambient temperature compensatedbimetallic element arranged to control a pair of electrical contacts, asource of variable voltage, a heating element mounted on said bimetallicelement and connected between said source of voltage and one of saidcontacts, a second heating element for said bimetallic element beingconnected between said contact and the other terminal of said source ofvoltage, a thermally actuated indicating instrument having a pointercontrolled by a U- shaped bimetallic element having heater windings oneach leg thereof, one of said heating elements being connected betweenthe other of said electrical contacts and one terminal of said source ofvoltage, the other of said heating elements being connected in seriesbetween one terminal of said source of voltage and the second mentionedheating element associated with said rst mentioned bimetallic element.

3. The combination comprising an ambient temperature compensatedbimetallic element provided with a plurality of series connected heatingelements, a source of variable voltage, a pair of contacts controlled bysaid bimetallic elements, one of said contacts being connected to thecommon juncture between said heating elements and one terminal of saidsource of voltage, the remaining terminals of said heating elementsbeing connected to opposite terminals of said source of voltage, and anelectric circuit connected between the4 other of said contacts and saidsource of voltage in parallel with one of said heating elements'gtherebyto produce increased current ilowing `through the other of said heatingelements proportional to a decrease in voltage of said source.

CHARLES VJ. KLUG.

References Cited in the-le of this patent UNITED STATESK PATENTS NumberName Date 1,401,049 Conklin Dec. 20, 192]`

